Your approach is definitely understandable. For some time I also thought I was also missing potassium and started to dose K2SO4 to make up for my deficency.

But with the EI dosing I worked out by molecular mass that it would be a ratio of 1: .08 : .15 of NPK. Which should be sufficient. The numbers might be off a little. I have to find my notes but my point is that the potassium is not at at a level that's below the minimum threshold.

Also I never noticed any difference when adding or not adding K2SO4 as long as I use the EI routine

The beauty of EI to me is that you don't really have to test that much (or at all). Wondering about ratios, etc. etc is great if you like to treat your tank like a test tube, but in reality every tank is different and you simply don't know that. If you dose high-end EI and are religious about water changes, etc you will eliminate 95% of any issue that develop. If I had to worry about testing every parameter I would have quit this hobby a long time ago.